1. Field of The Invention
The present invention relates to a method for estimating a heart rate variability and an apparatus for embodying such estimation, and more particularly to a method for estimating a heart rate variability and an apparatus for embodying such estimation which can be operated at a low sampling frequency and by which a heart rate variability (HRV) can be easily estimated from electrocardiogram data.
2. Description of The Related Art
In the field of medical procedure, HRV has been utilized heretofore in a diagnosis for heart diseases and the like. In this respect, a variety of manners for estimating an HRV from electrocardiogram data have been proposed.
As a conventional manner for estimating an HRV from electrocardiogram data, for example, a manner for estimating an HRV wherein peaks R on a waveform are detected from electrocardiogram data as shown in FIG. 1, and an inverse number of a time interval between peaks R is multiplied by 60 for estimating the number of beat in heart beats per minute has been known.
More specifically, in the above described manner, when it is assumed that a time instant when a peak R appears is represented by t.sub.i (i=0, 1, . . . , n), an HRV is determined by vectors [60/(t.sub.1 -t.sub.0, 60/(t.sub.2 -t.sub.1), . . . , 60/(t.sub.n -t.sub.n-1)].sup.t.
Accordingly, peaks R on a waveform must be detected correctly from electrocardiogram data in the above described conventional manner, so that such a problem that a sampling frequency for detecting peaks R on a waveform becomes high in the case where an apparatus for estimating an HRV is constituted by utilizing a conventional manner, resulting in a complicated structure of the apparatus, besides it results in a high cost has been pointed out.